Carburetor fuel bowl transfer tube



March 7, 1961 M. F. STERNER CARBURETOR FUEL BOWL TRANSFER TUBE Filed June 11, 1958 3 Sheets-Sheet 1 INVENTOR. Ma w/v/f'f 715mm March 7, 1961 STERNER 2,973,947

CARBURETOR FUEL BOWL TRANSFER TUBE Filed June 11, 1958 3 Sheets-Sheet 2 /2 46 WW 7777777777 32v- J59 w g4 l/M/L/ I: /30 5 c: B

1N VENTOR. Z1 4 Ala vwfjmems/e ATTORNEY March 7, .1961 M. F. STERNER CARBURETOR FUEL BOWL TRANSFER TUBE 3 Sheets-Sheet 3 Filed June 11, 1958 INVENTOR. M154 V/A fjmP/m? A 770/?A/E y CARBURETGR FUEL BOWL TRANSFER TUBE Melvin F. Sterner, Bloomfield Hills, Mich, assignor to Holley Carburetor Company, Van Dyke, Mich., a corporation of Michigan Filed June 11, 1958, Ser. No. 741,303

3 Claims. (Cl. 261-23) This invention relates generally to carburetors for .internal combustion engines, and more specifically to those carburetors having two or more fuel bowls associated therewith.

'Fhose carburetors which have a plurality of fuel bowls are usually of the multi-stage variety. That is, they usually have primary induction passages which are supplemented by secondary and even tertiary induction passages. The control of flow through the secondary and tertiary passages is accomplished by either manual or automatic means.

The usual fuel supply system is comprised of individual fuel bowls which in turn supply the correct amounts of fuel for the air which is flowing through the various induction passages. These fuel bowls have their own inlet means and are controlled by suitable float mecharusms.

The problem that exists in all of these carburetors having this general arrangement is that of an excessive fuel level in the secondary and/or tertiary fuel bowls, which often results in the spilling of fuel through the secondary fuel nozzles or the fuel bowl vents.

This problem will be better understood with a brief explanation of the general operation of a carburetor in which the problem is inherent. First, the fuel is pumped from the fuel tank to the individual fuel bowls at some minimum pressure which will vary with the particular carburetor and fuel pump design. Secondly, most of the driving is done in the range which requires only primary induction passage operation." Thirdly, most fuel bowl inlet systems are controlled by a needle valve, which in turn'is controlled by a float mechanism within the fuel bowls.

When the carburetor is used continuously in that range where only primary induction passage operation is required, the primary inlet valve will be open, but the fuel pump will continue to exert a force against the fuel inlet needle for the secondary bowl tending to unseat it. Since the secondary bowls are not supplying any ap preciable amounts of fuel during this range of engine operation, the fuel level within the secondary bowl may ultimately exceed the predetermined safe'level by virtue of the excess fuel being forced in by the fuel pump. One reason for this may be that it is not always economically practical to provide a needle valve capable of a positive or absolute seal, even when the float is at the maximum desired fuel level. Other contributing factors which further aggravate this problem are dirt between the inlet needle and the coacting seat and tilting and vibration of the float due to road bumps, etc.

The rate at which this excess fuel is admitted will determine the seriousness of the consequences. That is, if the rate is slow, the excess fuel may merely be forced The secondary induction passage 18 has a venturi 70,

2,973,947 Patented Mar. 7, 1-961 out of the main fuel nozzles within the secondary passages. However, since no air is flowing through the secondary induction passages, this fuel will-,puddle" there and vaporize, creating fumes which are ignitable externally of the engine. If the rate is relatively fast, fuel, in addition to that amount flowing out of the main nozzles, may actually spill. out of the fuel bowl vents onto the hot engine.

Accordingly, it is an object of this invention to provide means which will prevent the secondary fuel bowls from spilling this excess fuel.

More specifically, it is an object of this invention to provide means which will automatically prevent fuel spillage through the main nozzle system and the fuel bowl vents.

Other objects and advantages of the invention will become apparent whenreference is made to the following specification and the drawings, wherein:

Figure l is a top plan view of a multi-stage carburetor embodying t .e invention.

Figure 2 is a cross-sectional view taken substantially on the plane of line 2--2 of Figure 1, and looking in the direction of the arrows.

Figure 3 is a side-elevational view with portions thereof broken away and in cross-section, the cross-section being taken on the plane of line 3-3 of Figure 1 looking in the direction of the arrows.

.igure 4 is a perspective cross-sectional View taken on the plane of line i-4 of Figure 2 and looking in the direction of the arrows.

Figure 5 is a perspective cross-sectional view taken on the plane of line 55 of Figure. 2 and looking in the direction of the arrows.

Figure 6 is a partial schematic illustration of the invention, as viewed during a certain period of operation.

Figure 7 is a partial schematic illustration of a modification of the invention, as viewed during a certain 1 period of operation.

Referring now in greater detail to the illustrations, Figure l is a top plan view of a multi-stage carburetor 10 comprising a body 12 with the usual primary induction passages 14 and 16 and secondary induction pas sages 18 and 20 extending therethrough. The air intake 22 provided for the primary induction passages is adapted to be controlledby a choke plate 24 mounted on a rotatable shaft 26 whose position is controlled by a choke control assembly 28.- A primary fuel bowl 39 is mounted on the body 12 oppositely to the secondary fuel bowl 32. A conduit 34 conveys fuel from inlet 36 on'the primary bowl to theinlet 38 of the secondary bowl.

Figure 2, which is taken on line 22 of Figure 1, better illustrates the typical arrangement of the various elements within the carburetor. Primary induction passage 14 is illustrated as having a venturi 40, a main nozzle'42 and a manually controlled throttle valve 44 therein. The manner of manually controlling the throttle valve 44 is well known and need not be shown.

The main nozzle 42 communicates with the fuel within chamber 46 formed by the hollow fuel bowl 30 through the conduits 43, 59 and 52 and metering resrtiction 54. The idle fuel system, which includes a port 56 and transfer port 58 opening into the induction passage 14, communicates with chamber 46 by means of conduits 60, 62, 64and 66, and the'metering restriction a main nozzle 72 and a throttlevalve 74, the latter being either manually or automatically controlled by means well known in the art. Nozzle 72 communicates with chamber 76 of bowl 3?. by means of conduits 78, 8t) and 82, and metering restriction 84. An idle fuel system, similar to the one in the primary passage, is comprised of a port 85 and transfer port 86 opening into the secondary passage, and being supplied by conduits 87, 38, 89 and 90, and metering restriction 92.

Some carburetors do not have a secondary idle fuel system, in which case the above described problem of spill-over is amplified. Such carburetors may have only a transfer port, as illustrated at 86, which provides fuel only after the secondary throttle has moved some predetermined amount in the opening direction.

It should be mentioned that the various metering restrictions and conduits form no part of this invention and that they are therefore illustrated schematically. In fact, all of the structure described above is well known in the art, and it has been described only in suflicient detail to enable a better understanding of the invention as trates what may be called a transfer tube 94 having ends 96 and 98 thereof disposed in chambers 46 and 76 of fuel bowls 30 and 32, respectively. The tube 94 as illustrated is disposed substantially above the normal level of the fuel within either fuel bowl, and it is important that any modification of this invention be so constructed. Preferably, the tube should be at a substantial distance above the normal fuel level and yet below the level of the main fuel nozzles. The reason for this will become more apparent when the operation of the invention is considered.

It is apparent that instead of a continuous tube extending through the carburetor, separate tubes of approximate length may be pressed into opposite ends of a passage cored into the carburetor body, the result in either case being an unrestricted passage.

Figure 4 illustrates the construction of a typical primary fuel bowl having a hollow outer housing 30 to provide a fuel chamber 46 and containing a float 100, which is secured to an arm 102 pivoted at 104 and resiliently urged in a clockwise direction by spring 106. Fuel is supplied to the inlet 36 which communicates with a conduit portion 168 adapted to be controlled by a needle valve assembly 110. The needle assembly is substantially comprised of a body 112 having an inlet 114 and outlet ports 116 communicating with each other and controlled by a needle valve 118 slideably received in said body. The end 96 of transfer tube 94 is shown as extending into the chamber 46.

Figure 5 illustrates the construction of a typical secondary fuel bowl. All of the elements which are like or similar to those of Figure 4 are identified with like numerals. The only difference is that the float 100 of Fig.

5 rotates counterclockwise instead of clockwise to stop The ends 96 and 98 of transfer tube 94 are placed within fuel bowls 30 and 32 in such a position so as to be at a level which is substantially above that of the normal fuel level and yet below the level of the main nozzles. This is because the main purpose of the invention is not to fill an abnormally low bowl from the other bowl, but to drain the bowl having the excessive level (usually the secondary bowl) into the other bowl.

Assuming now that some condition causes the secondary fuel bowl 32 to receive excessive amounts of fuel, it becomes readily apparent that the level of the fuel in bowl 32 will rise. As soon as the level rises to the end 98, fuel will be transferred through the tube 94 in a manner so as to spill-off intochamber 46 of bowl 30.

Since the fuel in bowl 30'is being constantly utilized, this excessive amount of fuel from bowl 32 being transferred to bowl 30 will merely be utilized in the normal course of primary throttle operation.

As was mentioned previously, the preferred embodiment of this invention has the ends 96 and 98 of tube 94 projecting a substantial amount into their respective fuel bowls. The purpose of this is to minimize or completely eliminate any transfer of fuel from one fuel bowl to another when the fuel level in the first bowl is temporarily disturbed by cornering of the vehicle or by the carburetor being angularly displaced, as when the vehicle is on an incline. Reference to Figure 6 will illustrate this condition in schematic form. It will be noted that the ends 96 and 98 are illustrated as projecting into their respective bowls an equal amount; however, this is not necessary because under certain conditions resulting from varying carburetor, fuel bowl or vehicle characteristics, it may be desirable to have the ends 96 and 98 of different lengths. It may also be desirable to have the ends 96 and 98 at different levels, so long as each is substantially above the normal fuel level of the bowl in which the end is located.

Figure 6 also illustrates the tube 94 as having its ends 96a and 98a extended to within close proximity of the opposite sides of the fuel bowls. The degree of projection of the ends of the tube 94 will vary according to the specific carburetor design.

Another modification of the invention is illustrated in Figure 7 which shows the tube 94 having its one end 96 projecting into the fuel bowl while the other end 98 terminates in the aperture in the fuel bowl wall designed to receive the tube. This modification is particularly adaptable to those situations where it is desirable to have a quicker flow response in one direction through the tube 94 than in the other direction. In Figure 7, for instance, flows induced by an angular displacement of the carburetor such that the secondary fuel bowl is elevated above the primary bowl will have the quicker response.

While but two modifications of the invention have been disclosed and discussed, it is apparent that other modifications of the invention are possible without exceeding the scope of the invention as defined by the appended claims.

What I claim is:

1. In a carburetor having a main body portion with induction passages therethrough, a plurality of fuel bowls having means for maintaining normal fuel levels therein located substantially at opposite sides of said main body, conduit means communicating between said fuel bowls at a level substantially above that of said normal fuel level within said fuel bowls, said conduit means having one end thereof terminating in the wall of one fuel bowl and the other end projecting a substantial distance within the other fuel bowl.

2. In a carburetor, primary and secondary induction passages with throttle valves controlling the flow of combustible mixtures therethrough, primary and secondary fuel chambers adapted to supply fuel to said primary and secondary induction passages respectively, main fuel nozzles located within said induction passages and communicating with said fuel chambers, and a conduit con-- bustible mixtures therethrough, primary and secondary fuel chambers adapted to supply fuel to said primary and secondary induction passages respectively, main fuel nozzles located within said induction passages and communicating with said fuel chambers, and a conduit connecting the primary and secondary fuel chambers and having its open ends disposed within said fuel chambers at a level between that of said main fuel nozzles and the normal level within said chambers, said open ends of References Cited in the file of this patent UNITED STATES PATENTS Olson et al. Nov. 20, 1956 

